The present invention relates to a dielectric filter used in communications equipment and a method of manufacturing the dielectric filter. Also, the present invention relates to a protection film for covering the edges of the filter's electrodes
Conventionally, dielectric filters have an island-like input/output electrode, isolated from an external electrode, disposed on the outer side face of dielectrics having multiple through holes from the top to bottom.
One problem faced with a conventional dielectric filter is the peeling of the outer edge of the input/output electrodes and the inner edge of the external electrode of the dielectric filter, which may occur due to external stress, such as heat and twist applied to printed wiring boards when the dielectric filters are mounted to the printed wiring boards.